Bupropion hydrochloride, (xc2x1)-1-(3-chlorophenyl)-2-[(1,1-dimethylethyl)-amino]-1-propanone hydrochloride, is the active ingredient of Wellbutrin(copyright) which is marketed in the United States for the treatment of depression. It is also the active ingredient of Zyban(copyright) which is marketed in the United States as an aid to smoking cessation. Bupropion is a relatively weak inhibitor of the neuronal uptake of noradrenaline (NA), serotonin and dopamine (DA), and does not inhibit monoamine oxidase. While the mechanism of action of bupropion, as with other antidepressants, is unknown, it is presumed that this action is mediated by noradrenergic and/or dopaminergic mechanisms. Available evidence suggests that Wellbutrin(copyright) is a selective inhibitor of noradrenaline (NA) at doses that are predictive of antidepressant activity in animal models. See Ascher, J. A., et al., Bupropion: A Review of its Mechanism of Antidepressant Activity. Journal of Clinical Psychiatry, 56: p. 395-401,1995. 
Bupropion is extensively metabolized in man as well as laboratory animals. Urinary and plasma metabolites include biotransformation products formed via hydroxylation of the tert-butyl group and/or reduction of the carbonyl group of bupropion. Four basic metabolites have been identified. They are the erythro- and threo-amino alcohols of bupropion, the erythro-amino diol of bupropion, and a morpholinol metabolite. These metabolites of bupropion are pharmacologically active, but their potency and toxicity relative to bupropion have not been fully characterized. Because the plasma concentrations of the metabolites are higher than those of bupropion, they may be of clinical importance.
The morpholinol metabolite (+/xe2x88x92)-(2R*,3R*)-2-(3-chlorophenyl)-3,5,5-trimethyl-2-morpholinol hydrochloride is believed to be formed from hydroxylation of the tert-butyl group of bupropion. 
It has now surprisingly been discovered that despite the (xe2x88x92) form of the morpholinol metabolite predominating significantly in human plasma samples, it is the (+) enantiomer, (+)-(2S,3S)-2-(3-chlorophenyl)-3,5,5-trimethyl-2-morpholinol in which the activity resides.
Thus the present invention provides, in one aspect, the compound of formula (I), (+)-(2S,3S)-2-(3-chlorophenyl)-3,5,5-trimethyl-2-morpholinol or pharmaceutically acceptable salts and solvates thereof. 
Another aspect of the invention is pharmaceutical compositions comprising a compound of formula (I) or pharmaceutically acceptable salts and solvates thereof together with one or more pharmaceutically acceptable carriers, diluents or excipients.
A further aspect of the present invention is the use of a compound of formula (I) or pharmaceutically acceptable salts and solvates thereof in therapy.
Yet another aspect of the invention provides methods of treating depression, attention deficit hyperactivity disorder (ADHD), obesity, migraine, pain, sexual dysfunction, Parkinson""s disease, Alzheimer""s disease, or addiction to cocaine or tobacco products in a mammal (human or animal subject) comprising the administration to said subject of an effective amount of a compound of formula (I) or pharmaceutically acceptable salts and solvates thereof or pharmaceutical compositions thereof.
Yet another aspect of the present invention is the use of the compound of formula (I) or pharmaceutically acceptable salts and solvates thereof or pharmaceutical compositions thereof in the preparation of a medicament for the treatment of depression, attention deficit hyperactivity disorder (ADHD), obesity, migraine, pain, sexual dysfunction, Parkinson""s disease, Alzheimer""s disease, addiction to cocaine or tobacco products.
Yet another aspect of the present invention provides a method of treatment of addiction to alcohol in a mammal (human or animal subject) comprising the administration to said subject of an effective amount of a compound of formula (I) or pharmaceutically acceptable salts and solvates there